RSIT – knowledge-based support of high-crash site investigation

Road intersections and segments identify and as experiencing high number of crashes are investigated to identify roadway and traffic control deficiencies and relevant safety countermeasures. Site investigators must rely on their experience and judgment which may be an overwhelming task to those who lack such an experience. This paper presents a concept of a tool, called Road Site Investigation Tool (RSIT) that assists less experienced investigators as well as saves time of more experienced ones. A prototype of the tool developed for two-way stop-controlled intersections is introduced and evaluated. A knowledge base is represented in the form of a tree, where branches form sequences of checks (nodes) leading to specific countermeasures. The knowledge base for two-way stop-controlled intersections was acquired from several guidelines and manuals for road safety audits. A graphical user interface (GUI) was developed to facilitate the knowledge base application to site investigations. It has several functions for guiding the user through the investigation and documenting the outcome. The method evaluation indicated that the tool is easy to understand even to non-experts. The time spent on the investigation process with RSIT was shorter than with the traditional safety audit while the results of the two teams of experts and non-experts equipped with RSIT were similar.